This invention relates to latch arrangements for closures such as automotive doors and tailgate locks, and is particularly, although not exclusively, useful with electronic central locking systems for vehicles. The inventions disclosed in this application concern components of the latches, systems incorporating such components, and methods of manufacture of latch arrangements. Generally, the purpose of each invention is to simplify and render more compact such latch arrangements, in order to reduce their cost and to reduce vehicle weight.
Electronic central locking systems are well known, and a typical such system is disclosed for example in GB-A-2167482; an improvement is disclosed in our PCT publication WO97/28338. These systems provide central control of the locking and unlocking of vehicle doors and other closures such as tailgates, bonnets and petrol caps, amongst other vehicle functions such as lights. They interact mechanically with the conventional locking mechanisms which usually comprise, for some doors, an external key mechanism and an internal door locking knob. Interior and exterior door handles are rendered inoperable or neutral by such locking mechanisms.
Vehicle door latches are disclosed for example in our own applications WO97/19242 entitled xe2x80x9cLatch and Latch Actuator Arrangementsxe2x80x9d, WO97/19243 entitled xe2x80x9cLatch Arrangement suitable for an Automobile Doorxe2x80x9d and WO97/28337 entitled xe2x80x9cLatch Actuator Arrangementxe2x80x9d. An electric motor incorporated within the latch, and usually controlled by the central locking arrangement, drives a mechanism for unlocking and locking the latch. A problem with door latches manufactured in accordance with other patent publications, such as EP-A-397966 (Roltra-Morese Spa) and GB-A-2221719 (Kiekert GmbH and Co Kommanditgesellschaft) has been size, weight and complexity.
Further, whilst mechanisms for using an electric motor to complete the closure of a partially-closed door are known as such, for example from U.S. Pat. No. 5423582 (Kiekert GmbH and Co Kommanditgesellschaft), and systems for using an electric motor to release the latch and allow the door to open are also known, for example from EP-A-625625 (General Motors Corporation) which discloses power-assisted door opening and closing, none of these prior systems has been hitherto capable of integration with electronic central locking. Some of the present inventions disclosed in this application provide integrated electric central locking and electric door opening and/or closing, and even the possibility of using a common electric motor for all these functions. This represents a substantial improvement to the state of the art.
To illustrate the possible saving in the number of latch components required to be assembled in manufacture, it can be seen for example from EP-A-743413 (Rockwell Light Vehicle Systems (UK) Limited) entitled xe2x80x9cVehicle Door Latch Assemblyxe2x80x9d that a very large number of components is typically required in a vehicle door latch. The present inventions reduce significantly the number of components, by simplifying the mechanical operation of the latch and its interaction with electric motor drive.
It is an important security feature that all electrically-operated drive systems, such as locking and door opening or closing, can be overridden by corresponding manual mechanical drive, as appropriate, in case of electrical malfunction or jamming. Each separate invention is capable of being used in a latch with full mechanical override.
Double locking or so-called deadlocking or xe2x80x9csuper lockingxe2x80x9d mechanisms for vehicle doors are known as such. If the door has been locked by the key mechanism or electronic central locking, then it cannot be unlocked by the interior door knob. It can be unlocked by the interior door knob only if it has previously been locked by the door knob. To achieve this efficiently and simple, an embodiment of the present invention provides an automoblie door latch having a deadlocking arrangement.
Existing door latches for vehicles generally include components within a housing, and components extending outside the housing which make the arrangement bulky. As shown for example in Kiekert U.S. Pat. No. 5419597, the levers which cause the latch to release and the door to open, and which are connected to door handles by cables, generally project from the latch housing. We have discovered that it is possible to simplify the latch arrangement and to accommodate door handle-operated levers inside the latch housing, by providing a common axis of rotation for the latching pawl (sometimes denoted by the general term xe2x80x9clocking memberxe2x80x9d), the pawl release lever connected to the door handle, and preferably also a rotary coupling member for selectively coupling the pawl release lever to the pawl.
Door latches typically comprise housings to which components are permanently riveted, so that the door latch cannot be disassembly non-destructively. An embodiment of the present invention overcomes this problem, and also simplifies the process of assembly, by providing a latch assembly whose housing has a retaining means for retaining parallel plates releasably.
In some door latch arrangements incorporating electrically-powered actuation members for locking and unlocking, locking and unlocking is temporarily blocked if one of the door handles is pulled, but is unblocked once the handle is released. It then becomes necessary to repeat the actuation for locking or unlocking. In order to overcome this problem, an invention enables such actuation to be continued fully to completion once the handle has been released, without the need to repeat the actuation. To achieve this, the an embodiment of the present invention provides a latch arrangement.
In order to couple electric motor drive to various appropriate actuation members within the latch assembly, for door opening and/or closing and/or for locking and unlocking or other functions such as child-safety locking, we have discovered that a rotary indexing mechanism is particularly useful, in which there is resilient coupling between formations in the driving actuators and formations on the rotary indexing mechanism. The resilience of this coupling allows the continued rotation of the indexing mechanism past the actuator once actuation has been completed over a phase of rotation of the indexing mechanism, and prevents jamming. It also simplifies the mechanical arrangement, by allowing positional tolerance. Accordingly, an embodiment of the present invention provides a latch assembly.
Some existing door latch arrangements provide for so-called panic door opening, by which the door can be unlocked by the operation of the interior door handle without the need to lift the interior door knob. The door then remains unlocked to ensure that the door can be opened by the exterior door handle. This prevents inadvertent locking out of the vehicle by the occupant. Usually, the door latch will be unlocked when the vehicle is in motion, but there may be circumstances in which it is locked with the vehicle stationary or even moving. Another embodiment of the present invention enables panic door opening to be provided in a latch arrangement of compact and simple design.
A particularly important invention is the combination of electric locking and electric door latch release (door opening) using a common electric motor. The embodiment also provides electrically-powered door closing, using the same electric motor. Preferably also such latch arrangements provide selective electrical control of interior or exterior door handles, for example, for door opening, and preferably they also provide electrically-operable child-safety.
Latch arrangements typically comprise a latch bolt, for engaging a fixed striker in the door frame, and a latching pawl for releasably holding the latch bolt so as to latch the bolt. Electric door opening can then be achieved by actuating the latching pawl. We have discovered a particularly beneficial arrangement for electrical door latch release and door opening, using a linear actuator acting directly on the latch pawl, this arrangement allowing independent door opening by external mechanical means such as the door handle.
Another embodiment of the present invention provide an alternative beneficial arrangement for electrical door latch release on manual door opening, using a rotary actuator acting directly on the latch pawl.
Electrically-powered door closing requires application of the drive to the latch bolt which then pulls on the fixed striker to draw the door to its fully closed position. We have found that a particularly beneficial arrangement is to have a rotary actuator, under electric power, acting on the latch bolt. Preferably, the arrangement also provides door opening, i.e. the same electrical drive, and preferably the same rotary actuator, is used to release the latch pawl to allow the door to open.
As a beneficial alternative to the arrangement using a rotary actuator, an embodiment of the present invention also provides a linear actuator acting directly on the latch bolt, again with optional door opening.
With all of these arrangement, there is preferably a full mechanical override of any electrical function, i.e. mechanical actuation is independent.
With door latching arrangement there is a danger of inadvertent door locking when the door is slammed shut. This is particularly disadvantageous in electric central locking arrangements in which the locking of one door is linked to the locking of all doors. Existing anti-slam locking arrangements are generally quite complex, and the purpose of an embodiment of the present invention is to provide an anti-slam latching arrangement with all the advantages of compactness and simplicity of the other inventions. This is achieved by appropriately orientating a reciprocating sliding coupling member within the latch arrangement. Accordingly to the an embodiment of the present invention, anti-slam latching is latching is achieved differently, by ensuring that an actuator is prevented from moving within the latching arrangement whenever the arrangement is unlatched and the door open. The latching arrangement has a fixed formation which co-operates with the coupling actuator only at its unlocking configuration.